Conventionally, the stator of an inner rotor type motor has an annular stator core and coils. The stator core has tooth portions extending radially on the radially inner side of the stator, and the coils are would about the tooth portions. Japanese Laid-Open Patent Publication No. 11-18345 discloses a stator having a split core that is divided into pieces each corresponding to one tooth portion. A stator having a split core is spread flat when coils are wound about the tooth portions. Then, the split core pieces are annularly arranged such that the tooth portions are oriented radially inward, so that the stator is formed. In a stator having a split core, coils are wound about tooth portions with the stator being spread flat. This increases the space factor of the coils.
In the stator disclosed in Japanese Laid-Open Patent Publication No. 11-18345, a single lead wire is wound about each tooth portion. However, in the stator of Japanese Laid-Open Patent Publication No. 11-18345, both ends of every coil (lead wire) need to be connected to a predetermined conductive member, which complicates the wire connecting procedure.
As a technique for remedying the above drawback, the stator disclosed by Japanese Laid-Open Patent Publication No. 2002-176753 has a configuration in which a plurality of coils of the same phase are formed by a single lead wire, and a connecting wire extends between the coils. Each lead wire that constitutes the coils of one phase is connected at one end to a common neutral point, and receives at the other end the supply of alternating current of a 120 degree phase difference. Since this structure allows the number of the lead wires forming the coils to be less than the number of the tooth portions, the number of manufacturing steps for the lead wire connecting procedure of the ends of the wires is reduced.
However, in the stator of Japanese Laid-Open Patent Publication No. 2002-176753, coils of the same phase are arranged in the circumferential direction with a coil of another phase in between. This makes the connecting wire between the coils of the same phase relatively long. Therefore, in a circularization process of the stator and a connecting process that is performed after the circularization process to connect connecting wires, the connecting wires are likely to get entangled, making these processes troublesome. Also, in a stator having a split core, the stator is made annular from a spread flat state after coils are wound about the tooth portions. The length of each connecting wire therefore needs to have a sufficient margin. In other words, the length of the connecting wires need to be set relatively long.